I recently built this Thien Baffle for my Delta 50-786 dust collector. I mocked it up in Sketchup and then tweaked the design as I went. Had some scrap marine grade plywood that I used for the top and bottom, which is very smooth and works well. I used 1/8" thick acrylic around the sides of the separator chamber as well as on the top and bottom of the entry transition. My transition isn't a perfect round to square, it is more of an octagonal to square, but it seems to work fine.
Building this baffle with this style dust collector was a challenge, but luckily the plastic collector bag distorts out of the way. The entrance pipe is 4" and the exit is 6" with an air straightener made out of rockler t-track packaging.
I wanted to be able to remove the trash can portion without having to lift the baffle and dust collector so I came up with this wedge design. The trash can itself is attached to a sheet of plywood with a large hole in the center and then I made an angled frame around the outside. I put weather stripping on the underside of the top wedge to help make it airtight. The trash can is sitting on a yet-to-be-improved castor wheel cart. The whole thing just rolls under the baffle unit it is wedged tight.
Lastly I added a little window so that I can see how full the trash can is, and what happens to the dust after it falls below the baffle. All in all, it works well, I think. Thanks to everyone on this forum for the information on how to do this.
Inside
Transition
Wedge
Air straightener